User apparatus and transmission method

ABSTRACT

A user apparatus in a radio communication system supporting a D2D technology, includes a message generating unit configured to generate a message including a first segment and a second segment; and a message transmitting unit configured to transmit, multiple times, the message within a predetermined period, wherein information reported by a plurality of the first segments transmitted within the predetermined period by the message transmitting unit, is not changed within the predetermined period.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application and, thereby,claims benefit under 35 U.S.C. § 120 to U.S. patent application Ser. No.16/626,691 filed on Dec. 26, 2019, titled, “USER APPARATUS ANDTRANSMISSION METHOD,” which is a national stage application of PCTApplication No. PCT/JP2017/024413, filed on Jul. 3, 2017. The contentsof these applications are incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a user apparatus in a radiocommunication system.

BACKGROUND ART

In LTE (Long Term Evolution) and successor systems of LTE (for example,LTE-A (LTE Advanced) and NR (New Radio) (also referred to as 5G)), a D2D(Device to Device) technology in which user apparatuses directlycommunicate with each other without involving a radio base station, isbeing studied.

D2D reduces the traffic between the user apparatus and the base station,and enables communication between the user apparatuses even when thebase station becomes unable to communicate in the event of a disaster,etc.

D2D is generally classified into D2D discovery (also referred to as D2Ddetection) for finding other communicable user apparatuses and D2Dcommunication (also referred to as D2D direct communication,inter-terminal direct communication, etc.) for user apparatuses todirectly communicate with each other. In the following description, whenD2D communication, D2D discovery, etc., are not particularlydistinguished, these may be simply referred to as D2D.

Note that in 3GPP (3rd Generation Partnership Project), D2D is referredto as “sidelink”; however, in the present specification, D2D, which is amore general term, is used. However, sidelink is also used as necessaryin the description of the embodiment to be described later.

Furthermore, in 3GPP, studies are made to implement V2X (Vehicle toEverything) by extending the above D2D function, and the standardizationis being advanced. Here, V2X is a part of ITS (Intelligent TransportSystems), and as illustrated in FIG. 1, V2X is a generic term of V2V(Vehicle to Vehicle) meaning a communication mode performed betweenvehicles, V2I (Vehicle to Infrastructure) meaning a communication modeperformed between a vehicle and a road-side unit (RSU) installed on theroadside, V2N (Vehicle to Nomadic device) meaning a communication modeperformed between a vehicle and a mobile terminal of a driver, and V2P(Vehicle to Pedestrian) meaning a communication mode between a vehicleand a mobile terminal of a pedestrian.

In Rel-14 of LTE, standardization relating to several functions of V2Xhas been made (for example, Non-Patent Literature 1). In thisspecification, Mode 3 and Mode 4 are defined with respect to resourceallocation for V2X communication to the user apparatus. In Mode 3,transmission resources are dynamically allocated by DCI (DownlinkControl Information) sent from the base station to the user apparatus.Furthermore, in Mode 3, SPS (Semi Persistent Scheduling) is alsopossible. In Mode 4, the user apparatus autonomously selects atransmission resource from the resource pool.

CITATION LIST Non-Patent Literature [NPTL 1]

-   3GPP TS 36.213 V14.2.0 (2017 March)

[NPTL 2]

-   3GPP TS 36.300 V14.3.0 (2017 June)

SUMMARY OF INVENTION Technical Problem

By the above-described D2D discovery, for example, a user apparatus B,which receives a D2D discovery message transmitted from a certain userapparatus A, can discover the user apparatus A and determine adestination ID of the user apparatus A.

Furthermore, it is considered that the user apparatus B measures theradio quality (for example, path loss) by receiving the D2D discoverymessage, and performs link adaptation. For example, the user apparatus Bcan select appropriate transmission parameters (for example,transmission power, MCS, transmission beam) for performing D2Dcommunication with the user apparatus A, by link adaptation.

It is also considered to apply the link adaptation by D2D discovery toV2X. However, in V2X, it is assumed that each user apparatus moves at ahigh speed, and therefore it is necessary to measure the radio qualityby receiving D2D discovery messages in short periods. For this purpose,the user apparatus needs to transmit D2D discovery messages in shortperiods. Furthermore, for example, in order to measure the path loss onthe receiving side, it is necessary to include information on thetransmission power of the transmission source, etc., in the D2Ddiscovery message.

However, if the D2D discovery messages including information aretransmitted in short periods, there is a first problem that the overheadof radio resources increases. Although it is conceivable to measure theradio quality by using the D2D communication, in this case also, thereis the first problem that the overhead of radio resources increases,similar to the case of using the D2D discovery message. The firstproblem is not limited to V2X; this problem may arise in D2D in general.

Furthermore, in V2X, a use case of transmitting a message such asCAM/BSM (CAM: Cooperative Awareness Message/Basic Safety Message)including the position information of the transmission source userapparatus, is being studied. This use case can be considered asdiscovery at the application layer. In such a use case, it is assumedthat the information to be transmitted in messages is frequently changed(for example, every time a message is transmitted).

However, the conventional D2D discovery message does not assume a usecase in which the information to be transmitted may be changedfrequently as in the above use case; for example, the resource size isfixed in the conventional D2D discovery message. Therefore, theconventional D2D discovery is not suitable for use cases assumed in V2X.That is, there is a second problem that a message transmissiontechnology suitable for a use case in which information to betransmitted may be frequently changed, is required.

The present invention has been made particularly in view of the secondproblem, and it is an object of the present invention to provide atechnology for enabling messages to be appropriately transmitted andreceived, even when information, which is transmitted in a message by auser apparatus on the transmitting side, may be frequently changed, inD2D.

Solution to Problem

According to the disclosed technology, a user apparatus in a radiocommunication system supporting a D2D technology is provided, the userapparatus including

a message generating unit configured to generate a message including afirst segment and a second segment; and

a message transmitting unit configured to transmit, multiple times, themessage within a predetermined period, wherein

information reported by a plurality of the first segments transmittedwithin the predetermined period by the message transmitting unit, is notchanged within the predetermined period.

Advantageous Effects of Invention

According to the disclosed technology, a technology is provided forenabling messages to be appropriately transmitted and received, evenwhen information, which is transmitted in a message by a user apparatuson the transmitting side, may be frequently changed, in D2D.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram for describing V2X.

FIG. 2A is a diagram for describing D2D.

FIG. 2B is a diagram for describing D2D.

FIG. 3 is a diagram for describing MAC PDU used for D2D communication.

FIG. 4 is a diagram for describing a format of an SL-SCH subheader.

FIG. 5 is a diagram for describing an example of a channel structureused in D2D.

FIG. 6A is a diagram illustrating an example of a structure of PSDCH.

FIG. 6B is a diagram illustrating an example of the structure of PSDCH.

FIG. 7A is a diagram illustrating an example of the structure of PSCCHand PSSCH.

FIG. 7B is a diagram illustrating an example of the structure of PSCCHand PSSCH.

FIG. 8A is a diagram illustrating a resource pool configuration.

FIG. 8B is a diagram illustrating a resource pool configuration.

FIG. 9 is a diagram illustrating a configuration example of a radiocommunication system according to an embodiment.

FIG. 10 is a diagram for describing a basic operation according to theembodiment.

FIG. 11A is a diagram illustrating an example of mapping between messagetype discovery and signal type discovery.

FIG. 11B is a diagram illustrating an example of mapping between messagetype discovery and signal type discovery.

FIG. 12 is a diagram illustrating an example (option 1) of a method ofmultiplexing a discovery message and a discovery signal.

FIG. 13 is a diagram illustrating an example (option 2-1) of a method ofmultiplexing a discovery message and a discovery signal.

FIG. 14 is a diagram illustrating an example (option 2-2) of a method ofmultiplexing a discovery message and a discovery signal.

FIG. 15 is a diagram for describing NW assist.

FIG. 16 is a diagram for describing the outline according to embodiment2.

FIG. 17 is a diagram illustrating an example (type 1) of a procedure oftransmitting a discovery message.

FIG. 18 is a diagram illustrating an example (type 2) of a procedure oftransmitting a discovery message.

FIG. 19 is a diagram illustrating an example (type 2) of a procedure oftransmitting a discovery message.

FIG. 20 is a diagram illustrating a transmission example (type 1) of adiscovery message.

FIG. 21 is a diagram illustrating a transmission example (type 2) of adiscovery message.

FIG. 22 is a diagram illustrating a transmission example (type 2) of adiscovery message.

FIG. 23 is a diagram illustrating a transmission example (type 2) of adiscovery message.

FIG. 24 is a diagram illustrating a transmission example (type 2) of adiscovery message.

FIG. 25 is a diagram for describing an association between discovery andcommunication.

FIG. 26 is a diagram illustrating an example of a functionalconfiguration of a user apparatus UE according to an embodiment.

FIG. 27 is a diagram illustrating a configuration example of atransmitting unit 101.

FIG. 28 is a diagram illustrating an example of a functionalconfiguration of a base station 10 according to an embodiment.

FIG. 29 is a diagram illustrating an example of a hardware configurationof the base station 10 and the user apparatus UE according to anembodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the drawings. Note that the embodiments described below aremerely examples, and embodiments to which the present invention isapplied are not limited to the following embodiments. For example, theradio communication system according to the present embodiment isassumed to be a system of a method complying with the LTE; however, thepresent invention is not limited to the LTE, but can be applied to othermethods. Note that in the present specification and the claims, “LTE”has a broad meaning including not only communication methodscorresponding to releases 8 to 14 of 3GPP, but also communicationmethods of the fifth generation (5G, NR) of release 15 and beyond.

Furthermore, although the present embodiment is mainly targeted at V2X,the technology according to the present embodiment is not limited toV2X, but is widely applicable to D2D in general. Furthermore, “D2D”includes the meaning of V2X. Furthermore, the term “D2D” is not limitedto LTE, but refers to general communication between terminals.

Furthermore, in the following description of the embodiments, theexisting D2D discovery defined in releases 12 to 14, etc., of 3GPP willbe referred to as “LTE-D2D discovery”.

Furthermore, the terms “discovery message” and “discovery signal” areused in the following embodiments 1 and 2; however, messages/signalshaving the same functions as these may be referred to by names otherthan these.

(Outline of D2D)

In the present embodiment, D2D is the basic technology, and therefore anoutline of D2D defined in LTE will be described first. Note that alsowith V2X, it is possible to use the technology of D2D described here,and the user apparatus according to the present embodiment can transmitand receive D2D signals according to the technology.

As already described, D2D is generally classified into “LTE-D2DDiscovery” and “D2D communication”. As for “LTE-D2D discovery”, asillustrated in FIG. 2A, a resource pool for a discovery message issecured for each discovery period, and the user apparatus transmits adiscovery message (discovery signal) in the resource pool. Morespecifically, there are Type 1 and Type 2b. In Type 1, a user apparatusUE autonomously selects a transmission resource from the resource pool.In Type 2b, a semi-static resource is allocated by higher layersignaling (for example, RRC signal).

As for “D2D communication”, as illustrated in FIG. 2B, resource poolsfor SCI (Sidelink Control Information)/data transmission areperiodically secured. The user apparatus on the transmitting sidereports, to the receiving side, the data transmission resource (PSSCHresource pool), etc., by SCI, with the resource selected from theControl resource pool (PSCCH resource pool), and transmits the data withthe data transmission resource. More specifically, there are Mode 1 andMode 2 with respect to “D2D communication”. In Mode 1, resources aredynamically allocated by (E)PDCCH sent from the base station to the userapparatus. In Mode 2, the user apparatus autonomously selects atransmission resource from the resource pool. The resource pool isreported by SIB or a predefined resource pool is used.

Furthermore, as described above, Rel-14 has Mode 3 and Mode 4 inaddition to Mode 1 and Mode 2. In Rel-14, it is possible to transmit SCIand data simultaneously (in one subframe) by resource blocks adjacent toeach other in the frequency direction.

In LTE, a channel used for “LTE-D2D Discovery” is referred to as PSDCH(Physical Sidelink Discovery Channel), a channel for transmittingcontrol information such as SCI in “D2D communication” is referred to asPSCCH (Physical Sidelink Control Channel), and a channel fortransmitting data is referred to as PSSCH (Physical Sidelink SharedChannel).

As illustrated in FIG. 3, MAC (Medium Access Control) PDU (Protocol DataUnit) used in D2D is composed of at least a MAC header, a MAC Controlelement, a MAC SDU (Service Data Unit), and Padding. The MAC PDU mayinclude other information. The MAC header is composed of one SL-SCH(Sidelink Shared Channel) subheader and one or more MAC PDU subheaders.

As illustrated in FIG. 4, the SL-SCH subheader is composed of MAC PDUformat version (V), transmission source information (SRC), transmissiondestination information (DST), and reserved bits (R), etc. V isallocated to the beginning of the SL-SCH subheader and indicates a MACPDU format version used by the user apparatus. In the transmissionsource information, information relating to the transmission source isset. In the transmission source information, an identifier relating toProSe UE ID may be set. In the transmission destination information,information relating to the transmission destination is set. In thetransmission destination information, information relating to the ProSeLayer-2 Group ID of the transmission destination may be set.

An example of the channel structure of D2D is illustrated in FIG. 5. Asillustrated in FIG. 5, resource pools of PSCCH and resource pools ofPSSCH used for “D2D communication” are allocated. Furthermore, resourcepools of PSDCH used for “LTE-D2D discovery” are allocated in periodslonger than the periods of the channels of “D2D communication”.

Furthermore, PSSS (Primary Sidelink Synchronization Signal) and SSSS(Secondary Sidelink Synchronization Signal) are used as synchronizationsignals for D2D. Furthermore, for example, PSBCH (Physical SidelinkBroadcast Channel) that transmits broadcast information including theD2D system band, the frame number, and resource configurationinformation, etc., is used for an outside coverage operation. PSSS/SSSSand PSBCH are transmitted in one subframe.

FIG. 6A illustrates an example of a resource pool of PSDCH used in“LTE-D2D discovery”. The resource pool is set by the bitmap of thesubframe, and therefore the image of the resource pool becomes an imageas illustrated in FIG. 6A. The same applies to resource pools of otherchannels. Furthermore, in PSDCH, transmission is repeatedly performed(repetition) while performing frequency hopping. The number ofrepetitions can be set, for example, from 0 to 4. Furthermore, asillustrated in FIG. 6B, the PSDCH has a PUSCH base structure and has astructure in which a DM-RS (demodulation reference signal) is inserted.

FIG. 7A illustrates an example of a resource pool of PSCCH and PSSCHused for “D2D communication”. In the example illustrated in FIG. 7A, inPSCCH, transmission is repeatedly performed twice including the firsttime, while frequency hopping. In PSSCH, transmission is repeatedlyperformed four times including the first time, while frequency hopping.Furthermore, as illustrated in FIG. 7B, PSCCH and PSSCH have a PUSCHbase structure, that is a structure in which DMRS is inserted.

FIGS. 8A and 8B illustrate examples of resource pool configurations inPSCCH, PSDCH, and PSSCH. As illustrated in FIG. 8A, in the timedirection, a resource pool is represented as a subframe bitmap.Furthermore, the bitmap is repeated as many times as num.repetition.Furthermore, an offset indicating the start position in each period isspecified. Note that the bitmap is also referred to as T-RPT(Time-Resource Pattern).

In the frequency direction, contiguous allocation and dis-contiguousallocation are possible. In the example of FIG. 8B, as illustrated, thestart PRB, the end PRB, and the number of PRBs (numPRB) are specified.

(System Configuration)

FIG. 9 is a diagram illustrating a configuration example of the radiocommunication system according to the present embodiment. As illustratedin FIG. 9, the radio communication system according to the presentembodiment includes a base station 10, a user apparatus UE1, and a userapparatus UE2. In FIG. 9, the user apparatus UE1 is intended for thetransmitting side of the discovery message/discovery signal, and theuser apparatus UE2 is intended for the receiving side of the discoverymessage/discovery signal; however, both the user apparatus UE1 and theuser apparatus UE2 have a transmitting function and a receivingfunction. Hereinafter, when not particularly distinguishing between theuser apparatus UE1 and the user apparatus UE2, the user apparatus issimply described as “user apparatus UE”. Furthermore, the user apparatusUE may be described as “UE” in some cases.

The user apparatus UE1 and the user apparatus UE2 illustrated in FIG. 9respectively have functions of cellular communication as the userapparatus UE in LTE (in addition to existing LTE, LTE including meaningof 5G, NR, the same applies hereinafter), and have a D2D functionincluding signal transmission and reception in the channels describedabove. Furthermore, the user apparatus UE1 and the user apparatus UE2have a function of executing the operations described in the presentembodiment.

Furthermore, the user apparatus UE may be any apparatus having thefunction of the D2D. For example, the user apparatus UE may be avehicle, a terminal held by a pedestrian, and an RSU (a UE type RSUhaving a UE function), etc.

Furthermore, the base station 10 has a function of cellularcommunication as the base station 10 in LTE, and a function (NW assistfunction) for enabling communication of the user apparatus UE accordingto the present embodiment. Furthermore, the base station 10 may be anRSU (eNB type RSU having the function of eNB).

Furthermore, the signal waveform used for D2D by the user apparatus UEmay be CP-OFDM (same as in DL in LTE), SC-FDMA (same as in UL in LTE),or other signal waveforms. In the present embodiment, it is assumed thatthe same SC-FDMA as in the UL of the LTE, is used in the D2D. Similar tothe UL of the LTE, the time direction resources in the D2D arerepresented by symbols, slots, subframes, etc., and the frequencydirection resources are represented by subcarriers, subbands, etc.However, in the present embodiment, symbols, slots, subframes,subcarriers, subbands, etc., need not be the same as UL of LTE.

(Basic Operation Example)

FIG. 10 is a diagram for describing a basic operation example relatingto discovery between user apparatus UEs according to the presentembodiment (including the embodiments 1 and 2). The “discovery message”used in the description is the discovery message of the embodiment 1 orthe embodiment 2, and the “discovery signal” is the discovery signal ofthe embodiment 1.

FIG. 10 illustrates a status where UE1 to UE6 are present. UE1 to UE5are located in neighboring areas indicated by A, and UE6 is located at aposition distant from UE1 to UE5.

Each of UE2 to UE6 transmits a discovery message and/or a discoverysignal. UE1 receives the discovery message and/or the discovery signaltransmitted from UE2 to UE5 and identifies the IDs (transmission sourceIDs) of UE2 to UE5. Furthermore, as an example, the discovery messageand/or the discovery signal includes the transmission power informationof the transmission source, and UE1 can measure the path loss (anexample of radio quality) of UE2 to UE5, by measuring the receptionpower of the discovery message and/or the discovery signal transmittedfrom UE2 to UE5.

For example, when UE1 detects that all of the path losses of UE2 to UE5are small (when it is detected that UE2 to UE5 are in a near range), UE1can determine to decrease the transmission power/MCS for performingtransmission in D2D communication with respect to UE2 to UE5.Furthermore, when the CSI of a specific UE that is the destination canbe identified, the UE1 can select an appropriate transmission beam. Notethat in order to implement reliable discovery, it is desirable that thediscovery range is sufficiently larger than the D2D communication range.

Note that the UE1 cannot receive the discovery message and/or thediscovery signal transmitted from the UE6, and therefore UE1 does notdiscover UE6.

Hereinafter, the embodiments 1 and 2 will be described as embodimentsrelating to discovery according to the present embodiment.

Embodiment 1 <Outline of Embodiment 1>

In the embodiment 1, hybrid discovery composed of signal type discoveryand message type discovery is introduced.

In the embodiment 1, a signal transmitted by signal type discovery isreferred to as a discovery signal, and a message transmitted by messagetype discovery is referred to as a discovery message.

The discovery signal transmitted in the signal type discovery is aphysical signal that does not include a message, similar to a referencesignal or a synchronization signal. However, the discovery signal is notlimited to a physical signal, and the discovery signal may be a messagehaving a small payload. The discovery message transmitted by messagetype discovery is a message including information such as an ASparameter, UE-ID, position information, etc. In the embodiment 1, thechannel for transmitting the discovery message is not particularlylimited; however, for example, the channel of D2D communication may beused. Furthermore, a channel of LTE-D2D discovery may be used.Furthermore, a newly defined channel may be used.

Basically, the user apparatus UE transmits both a discovery message anda discovery signal. The transmission period of discovery signals isindependent of the transmission period of discovery messages.“Independent of” means, for example, that the transmission period ofdiscovery signals and the transmission period of discovery messages areindependently determined. For example, the transmission period ofdiscovery signals is shorter than the transmission period of discoverymessages. In this case, for example, the transmission period ofdiscovery signals is 10 ms, and the transmission period of discoverymessages is 200 ms.

Furthermore, the transmission time (the time length of the resource usedfor one transmission, transmission duration) and the bandwidth (thefrequency width of the resource used for one transmission) of discoverysignals may be different from the transmission time and the bandwidth ofdiscovery messages. For example, the user apparatus UE transmits thediscovery signal over a wide bandwidth by using one OFDM symbol(hereinafter, symbol) or a plurality of symbols.

The discovery signal does not include a message, and therefore thediscovery signal can be transmitted in a short time. Therefore, even ifthe transmission period of the discovery signals is shortenedindependently of the transmission period of discovery messages, theincrease in overhead can be kept small.

The discovery message transmitted from the user apparatus UE1 on thetransmitting side includes, for example, information on resources usedby the user apparatus UE1 for transmitting discovery signals.Accordingly, the user apparatus UE2 on the receiving side receives thediscovery message transmitted from the user apparatus UE1, therebyidentifying the resource of the discovery signal transmitted from theuser apparatus UE1, and based on the resource, the user apparatus UE2can receive the discovery signal transmitted from the user apparatusUE1. Accordingly, for example, the user apparatus UE2 can identify thepath loss between the user apparatus UE1 and the user apparatus UE2.

The information on the mapping between the discovery message and thediscovery signal transmitted by a certain user apparatus UE, such as theabove resource information, may be provided to the user apparatus UE bythe base station 10. For example, the base station 10 transmits theinformation of the resource of the discovery signal transmitted by theuser apparatus UE1 to the user apparatus UE2, so that the user apparatusUE2 existing within the coverage of the base station 10, can receive thediscovery signal transmitted from the user apparatus UE1 withoutreceiving the discovery message transmitted from the user apparatus UE1.

Note that the information transmitted from the base station 10 to theuser apparatus UE in the NW assist is not limited to the information onthe discovery message/discovery signal. For example, the base station 10may transmit, to the user apparatus UE, mapping information between anytwo, or between any three or four of the discovery message, thediscovery signal, the control channel, and the data channel.

<Details of Discovery Message>

The user apparatus UE1 that is the transmission source may include, inthe discovery message to be transmitted, one or more transmissionparameters and/or one or more reception parameters used by the userapparatus UE1. The transmission parameter is a parameter used for signaltransmission by the user apparatus UE1, and the reception parameter is aparameter used for signal reception by the user apparatus UE1. Thetransmission parameter corresponds to the reception parameter on thereceiving side.

These parameters are parameters used in Access Stratum's protocol (PDCP,RLC, MAC, PHY, etc.) in the PC5 interface (Non-Patent Literature 2), forexample, and are referred to as AS (Access Stratum) parameters.

As AS parameters, for example, there are L1-ID (ID of layer 1) and L2-ID(ID of layer 2).

Furthermore, as the AS parameters for message type discovery, forexample, there is transmission power or transmission power density.Furthermore, as the AS parameters for signal type discovery, forexample, there are the following:

Frequency used for transmission or reception

Resources and configurations (for example, time/frequency resourcehopping pattern, periodicity, sequence) used for transmitting orreceiving discovery signals

Transmission power, transmission power density, transmission poweroffset relative to the transmission power of the discovery message.

One or any plurality of or all of the plurality of AS parametersdescribed above are included in the discovery message.

In hybrid discovery, the AS parameter of the discovery signaltransmitted by a discovery message from the user apparatus UE1 on thetransmitting side (for example, the configuration used by the userapparatus UE1 for discovery signal transmission, etc.) is useful for theuser apparatus UE2 on the receiving side of the discovery signal, andthe AS parameter can be used to receive (measure) the discovery signaltransmitted from the user apparatus UE1.

The discovery message transmitted from the user apparatus UE1 mayinclude the AS parameter of the PSCCH to be transmitted (or received) bythe user apparatus UE1 and/or the AS parameter of the PSSCH to betransmitted (or received) by the user apparatus UE1. In this case, theuser apparatus UE2 receiving the discovery message can use the ASparameter of the PSCCH and/or the AS parameter of the PSSCH fortransmission/reception of PSCCH/PSSCH. In this way blind detection canbe reduced. Furthermore, the performance of link adaptation/beam formingcan be improved. Furthermore, collision of resources can be reduced.

As AS parameters for D2D communication included in the discoverymessage, for example, there are the following parameters:

A frequency for transmission or a frequency for reception

Power gap between channels, power gap between signals

As AS parameters for D2D communication included in a discovery message,for PSCCH, for example, there are the following parameters:

Scrambling parameters

Transmission power or transmission power density

MCS

Resource size

Beam pattern, beam ID

Candidate resources (for example, resource pool).

Time during which reception may not be performed (D2D gap)

Reference signal configuration (for demodulation, for phasecompensation, etc.)

As AS parameters for D2D communication included in a discovery message,for PSSCH, for example, there are the following parameters:

Transmission power or transmission power density

MCS

Beam pattern, beam ID

Candidate resources (for example, resource pool).

Time during which reception may not be performed (D2D gap)

Reference signal configuration (for demodulation, for phasecompensation, etc.)

One or any plurality of or all of the AS parameters described above areincluded in the discovery message.

Hereinafter, an example of transmitting/receiving a discovery signal anda discovery message without performing NW assist will be described asthe embodiment 1-1, and an example of performing NW assist will bedescribed as the embodiment 1-2.

Embodiment 1-1

In a case where the user apparatus UE1, etc., transmits a discoverysignal and a discovery message, the user apparatus UE2 on the receivingside, which receives the discovery signal and the discovery message,needs to identify that the discovery signal and the discovery messagehave been transmitted from the same user apparatus.

Therefore, in the embodiment 1-1, the discovery signal and the discoverymessage are associated with each other as in option 1, option 2, oroption 3 described below.

<Discovery Signal/Discovery Message Association: Option 1>

In option 1, as illustrated in FIG. 11A, the transmission/receptionparameters of a discovery signal are derived from the transmissionparameters of a discovery message and/or the payload of the discoverymessage. Note that the transmission/reception parameter means aparameter used by the transmitting side for transmission and a parameterused by the receiving side for reception, which may be the same.

As illustrated in FIG. 11A, there are time offset, DMRS parameter,frequency position, hopping pattern, etc., as the transmissionparameters of the discovery message used for deriving thetransmission/reception parameters of the discovery signal.

For example, the user apparatus UE1 on the transmitting side transmits adiscovery message by using the transmission parameters selected by theuser apparatus UE1. Furthermore, according to a predetermined rule(mapping function in FIG. 11A), transmission parameters of a discoverysignal are derived from transmission parameters of a discovery message,and a discovery signal is transmitted by using the transmissionparameters.

The user apparatus UE2 that receives the discovery message estimates thetransmission parameters of the received discovery message.Alternatively, the user apparatus UE1 may include the transmissionparameters of the discovery message in the payload of the discoverymessage, and the user apparatus UE2 may acquire the transmissionparameters from the payload.

From the transmission parameters of the received discovery message, theuser apparatus UE2 derives the reception parameters of the discoverysignal according to the predetermined rule, and receives the discoverysignal by using the reception parameters. The user apparatus UE2identifies the discovery signal received by using the receptionparameters, as the discovery signal transmitted from the user apparatusUE1 that is the transmission source of the discovery message from whichthe reception parameters have been derived.

In option 1, compared with option 2, there is an advantage that thetransmitting side can flexibly select the transmission parameters of thediscovery message.

The discovery message and the discovery signal do not need to be one toone, and may correspond to 1:N. For example, a configuration may beconsidered in which a plurality of discovery signals with respect to acertain discovery message, are used for transmission by differenttransmission beams and/or reception beams and/or different panels(antenna groups, antenna ports). That is, to a certain discoverymessage, a plurality of discovery signals, which are transmitted bydifferent transmission beams and/or different reception beams and/ordifferent panels, are associated.

Furthermore, for example, when a discovery signal in a certaintransmission beam is applied, the user apparatus UE2 on the receivingside can perform discovery according to the communication range in thecase where the transmission beam is applied (the discovery range becomeswide). At this time, the discovery message may be transmitted by apredetermined port and/or transmission beam index. The discovery messagemay be repeatedly transmitted in order to compensate for the coveragedifference between the discovery message and the discovery signaldepending on the presence or absence of a beam. The number ofrepetitions may be a predetermined number of times. Furthermore, aperiodic switching pattern in terms of time (beam switching pattern) maybe applied to the transmission beam of the discovery signal.Accordingly, a beam diversity effect is obtained. Furthermore, byreporting the beam switching pattern of the discovery signal to the userapparatus UE2 on the receiving side with the discovery message, or bytransmitting the discovery signal with a predetermined beam switchingpattern, the user apparatus UE2 on the receiving side can also estimatethe channel quality for each transmission beam.

Information on the transmission beam and/or the transmission port of thediscovery signal can be reported by the discovery message. Furthermore,in a mode in which information on the transmission beam and/or thetransmission port of the discovery signal is not reported by a discoverymessage, it may be regarded that the configuration relating to thetransmission beam forming of the discovery signal such as thetransmission beam index and/or the transmission port, is the same asthat of the discovery message, or the association of transmission beamsbetween the discovery message and the discovery signal may be defined inadvance.

<Discovery Signal/Discovery Message Association: Option 2>

In option 2, as illustrated in FIG. 11B, the transmission/receptionparameters of the discovery message are derived from the transmissionparameters of the discovery signal.

As illustrated in FIG. 11B, there are time offset, sequence, frequencyposition, hopping pattern, etc., as transmission parameters of adiscovery signal used for deriving transmission/reception parameters ofa discovery message.

For example, the user apparatus UE1 on the transmitting side transmits adiscovery signal by using the transmission parameters selected by theuser apparatus UE1. Furthermore, according to a predetermined rule(mapping function in FIG. 11B), transmission parameters of a discoverymessage are derived from transmission parameters of a discovery signal,and a discovery message is transmitted by using the transmissionparameters.

The user apparatus UE2 that receives the discovery signal estimates thetransmission parameters of the received discovery signal.

From the transmission parameters of the received discovery signal, theuser apparatus UE2 derives the reception parameters of the discoverymessage according to the predetermined rule, and receives the discoverymessage by using the reception parameters. The user apparatus UE2identifies the discovery message received using the reception parametersas the discovery message transmitted from the user apparatus UE1 that isthe transmission source of the discovery signal from which the receptionparameters have been derived. Furthermore, when the discovery messageincludes the ID of the user apparatus UE1 that is the transmissionsource, the user apparatus UE2 can identify, based on the ID, that thetransmission source of the discovery signal is the user apparatus UE1having the corresponding ID.

Option 2 has the advantage of being able to quickly detect the discoverysignal compared to option 1.

<Discovery Signal/Discovery Message Association: Option 3>

In option 3, the transmission parameters and/or reception parameters ofthe discovery message and the transmission parameters and/or receptionparameters of the discovery signal associated with the discoverymessage, are set (configured) or preset (pre-configured) in the userapparatus UE1.

<Selection of Transmission Resource>

Regarding the transmission resource of the discovery message, forexample, the resource pool is set (configured) or preset(pre-configured) in the user apparatus UE1. With regard to setting(configuring) in the present embodiment, for example, it is assumed thata configuration is performed by the base station 10 for the userapparatus UE by RRC signaling, etc. Furthermore, with regard topresetting (preconfiguring) in the present embodiment, for example, itis assumed that settings are made in advance without the user apparatusUE receiving settings from the base station 10. Hereinafter, setting(configuring) or presetting (pre-configuring) is described as (pre)setting.

The user apparatus UE1 transmits a discovery message by using theresource selected from the resource pool. A resource pool for reception(which may be the same as the resource pool for transmission) is alsoset for the user apparatus UE2 on the receiving side. The resource poolfor reception may not be set for the user apparatus UE2 on the receivingside.

Furthermore, regarding the transmission resource of the discoverysignal, for example, a resource pool is (pre) set in the user apparatusUE1. The user apparatus UE1 transmits a discovery signal by using aresource selected from the resource pool. A resource pool for reception(which may be the same as the resource pool for transmission) is alsoset for the user apparatus UE2 on the receiving side. The resource poolfor reception may not be set for the user apparatus UE2 on the receivingside.

For example, the transmission resource pool of the discovery signal isdefined such that the discovery signal is transmitted by one symbol or aplurality of symbols in a certain slot.

In both cases of the discovery message and the discovery signal, thereare options 1 and 2 as methods by which the user apparatus UE1 selects atransmission resource from the resource pool. Which one of option 1 oroption 2 is to be executed, may be determined by an instruction from thebase station 10, or the one that is to be executed may be preset in theuser apparatus UE1.

In option 1, the user apparatus UE1 randomly selects a resource from theresource pool for the transmission of the discovery message/discoverysignal.

In option 2, the user apparatus UE1 makes a sensing-based resourceselection. In this case, for example, the user apparatus UE1 selectsresources satisfying the following conditions 1 and 2, as candidateresources.

Condition 1: RSRP or RSSI is less than the predefined (or (pre) set)threshold.

Condition 2: In a slot (or symbol) that is the time resource of theresource satisfying condition 1, RSRP or RSSI in a frequency resourceother than the frequency resource of the resource satisfying condition1, is lower than a threshold value determined in advance (or (pre) set).

Then, the user apparatus UE1 transmits a discovery message/discoverysignal using resources randomly selected from the resources satisfyingthe conditions 1 and 2.

Furthermore, the user apparatus UE1 may make a sensing-based resourceselection according to the method defined in Non-Patent Literature 1.

For example, there may be a plurality of transmission settings of adiscovery message and a discovery signal, from the viewpoint of the userapparatus UE1 on the transmitting side, and the user apparatus UE1 onthe transmitting side may transmit a discovery signal and a discoverymessage based on any setting, and may select an unused resource(setting) based on a sensing result, a measurement result, or a resultof decoding a discovery message, etc.

<Multiplexing Method>

As methods of multiplexing a discovery signal and a discovery message,there are options 1 and 2 as follows.

<Multiplexing Method: Option 1>

Option 1 will be described with reference to FIG. 12. As illustrated inFIG. 12, in this example, the discovery signal is transmitted in periodsshorter than the transmission periods of discovery messages.Furthermore, the discovery signal is transmitted by a transmissionbandwidth wider than the transmission bandwidth of the discoverymessage.

In the time resource indicated by A in FIG. 12, a part of the resourceof the discovery signal overlaps a part of the resource of the discoverymessage. When the resources overlap in this way, the user apparatus UE1drops the transmission of the discovery signal. That is, the userapparatus UE1 does not transmit a discovery signal in this timeresource.

<Multiplexing Method: Option 2>

Next, option 2 will be described. In option 2, a single symbol or aplurality of symbols in a discovery message are not transmitted. Thesingle symbol or the plurality of symbols are used for transmitting adiscovery signal. Hereinafter, options 2-1 and 2-2 will be described.

<Multiplexing Method: Option 2-1>

In option 2-1, one symbol or a plurality of symbols in a discoverymessage are not always transmitted. FIG. 13 illustrates an example. Asillustrated in FIG. 13, in this example, the last one symbol in thediscovery message is not always transmitted, regardless of whether thediscovery signal is transmitted. Note that the blank at the trailing endof the discovery message in FIG. 13 indicates a GAP in the slot (orsubframe).

<Multiplexing Method: Option 2-2>

In option 2-2, when the discovery signal overlaps the discovery message,the overlapping single symbol or a plurality of symbols are not used fortransmitting the discovery message.

An example is illustrated in FIG. 14. In the example of FIG. 14, in thetime resource indicated by A, a resource of one symbol in the discoverymessage overlaps the resource of the discovery signal. In this case, thesymbol is not used for transmitting the discovery message. On the otherhand, in the symbol at the time position indicated by B, the discoverysignal is not transmitted, and therefore the symbol is used fortransmitting the discovery message.

<Regarding Cross Carrier Transmission>

Discovery messages and discovery signals may be transmitted at differentfrequencies (carriers). For example, the user apparatus UE1 transmitsthe discovery message at a low frequency, and transmits the discoverysignal at a frequency higher than the frequency of the discoverymessage. The high frequency may be, for example, a frequency used in D2Dcommunication.

Furthermore, the discovery message and the discovery signal may betransmitted by different RATs. For example, the user apparatus UE1transmits the discovery message by the LTE sidelink and transmits thediscovery signal by the NR sidelink.

<Regarding Measurement>

In a case where both message type discovery and signal type discoveryare (pre) set for the user apparatus UE1 on the transmitting side and/orthe user apparatus UE2 on the receiving side, for example, the userapparatus UE2 on the receiving side performs measurement by a discoverysignal.

Alternatively, the user apparatus UE2 on the receiving side performsmeasurements on both the discovery signal and the discovery message, forexample, and calculates and uses the average of the measurement resultof the discovery signal and the measurement result of the discoverymessage. Note that even in the case of performing measurements on boththe discovery signal and the discovery message, with regard to the usageof the measurement result, only one of the measurement results may beused. Furthermore, for the measurement by the discovery message, theDMRS in the discovery message is used.

Furthermore, in a case where only message type discovery is (pre) setfor the user apparatus UE1 on the transmitting side and/or the userapparatus UE2 on the receiving side, the user apparatus UE2 on thereceiving side uses the DMRS in the discovery message to performmeasurements.

In a case where only signal type discovery is (pre) set for the userapparatus UE1 on the transmitting side and/or the user apparatus UE2 onthe receiving side, the user apparatus UE2 on the receiving sideperforms measurements by the discovery signal.

Embodiment 1-2

Next, an example in which NW assist is performed will be described asthe embodiment 1-2. Even in the case of performing NW assist, theembodiment 1-1 can be applied to the operation in which the userapparatus UE1 transmits a discovery signal/a discovery message, and theoperation in which the user apparatus UE2 receives (or measures) thediscovery signal/discovery message.

FIG. 15 is a diagram for describing the operation in the embodiment 1-2.As illustrated in FIG. 15, in step S101, the base station 10 transmitsconfiguration information to the user apparatus UE1. In step S102, thebase station 10 transmits configuration information to the userapparatus UE2. Transmission of the configuration information in stepsS101 and S102 may be performed by SIB common to the UEs, by UE specifichigher layer signaling (RRC message), by a MAC signal, or by DCI.

In step S103, the user apparatus UE1 transmits a discovery messageand/or a discovery signal based on the configuration informationreceived in step S101, and the user apparatus UE2 receives the discoverymessage and/or the discovery signal transmitted from the user apparatusUE1 based on the configuration information received in step S102.

The configuration information received by the user apparatus UE2 on thereceiving side in the above-described step S102 is, for example,parameters (for example, time/frequency resources, periods, sequences),etc., necessary for detecting the discovery signal. More specifically,there are options 1 and 2 as follows.

Option 1) In option 1, the configuration information received by theuser apparatus UE2 is a list of candidate parameter sets. In this case,for example, the user apparatus UE2 attempts to detect the discoverysignal by using each candidate parameter set in the list, and detectsthe discovery signal. Subsequently, for example, a discovery messagecorresponding to the detected discovery signal is received by using themapping function described in the embodiment 1-1, and the transmissionsource of the discovery signal and the discovery message is identifiedby an ID included in the discovery message.

Option 2) In option 2, the configuration information received by theuser apparatus UE2 is a list of “transmission source IDs and parametersets corresponding to the transmission source IDs”. In this case, theuser apparatus UE2 attempts to detect a discovery signal by using eachparameter set in the list, and detects the discovery signal. The userapparatus UE2 identifies the transmission source ID corresponding to theparameter set used when the discovery signal has been detected, as thetransmission source ID of the discovery signal.

In step S101, the configuration information received by the userapparatus UE1 on the transmitting side is, for example, the transmissionconfiguration (for example, time/frequency resources, periods, hoppingparameters, etc.) of the discovery signal and/or the discovery message.

In the above example, the base station 10 reports, to the UE side, boththe configuration information for receiving the discovery message and/orthe discovery signal and the configuration information for transmittingthe discovery message and/or the discovery signal; however, this is onlyan example. The base station 10 may report, to the UE side, either theconfiguration information for receiving the discovery message and/or thediscovery signal or the configuration information for transmitting thediscovery message and/or the discovery signal.

(Regarding Usage of Discovery in Embodiment 1)

The user apparatus UE can estimate, for example, the user apparatus UEthat is the destination of the D2D communication, by discovery. Forexample, the user apparatus UE can determine the destination UE based onthe measurement result (path loss) of the discovery message and/or thediscovery signal that is received and/or the location information of thetransmission source UE of the discovery message and/or the discoverysignal. For example, the user apparatus UE can determine, as thedestination, the UE that has the smallest path loss among the UEs in itsown heading direction.

Furthermore, the user apparatus UE2 performing transmission, such as D2Dcommunication, based on the discovery message and/or discovery signalthat is received, may determine the transmission parameters based on themaximum path loss, among the path losses in a group of user apparatusesUEs to be destinations that are identified from the discovery messageand/or the discovery signal that is received. Accordingly, it ispossible to appropriately perform data transmission (group cast,multicast, etc.) to the above group.

Note that when the user apparatus UE2 that has performed transmission byD2D communication, etc., receives a NACK for the MAC PDU from a certainUE, the user apparatus UE2 may adjust the transmission parameters inorder to improve the reliability.

As described above, in the embodiment 1, the transmission period of thediscovery message and the transmission period of the discovery signalare independent of each other, and discovery signals of short periodsand discovery messages of long periods are used, and therefore it ispossible for the user apparatus UE to appropriately measure the radioquality while avoiding an increase in the overhead of the radioresources.

Embodiment 2

Next, the embodiment 2 will be described. A message transmitted bydiscovery according to the embodiment 2 is referred to as a discoverymessage. The discovery message described in the embodiment 2 may be usedas a discovery message of the message type discovery of theembodiment 1. That is, the embodiment 1 and the embodiment 2 can beimplemented in combination. Furthermore, the discovery message of themessage type discovery of the embodiment 1 may be different from thediscovery message described in the embodiment 2.

<Outline of Embodiment 2>

The discovery message in the embodiment 2 has two or more parts, andeach part is separately encoded. However, it is not essential to encodethe parts separately. FIG. 16 illustrates an example where the discoverymessage includes two parts. As illustrated in FIG. 16, this discoverymessage includes segments #1 and #2.

At least one part (for example, segment #1) in the discovery message istransmitted with a fixed payload size by using a certain resource, andthe content of this part does not change within a certain time period.However, the redundancy version and beam forming can be changed withinthe period.

The user apparatus UE1 on the transmitting side repeatedly transmitsdiscovery messages in a predetermined time/frequency resource pattern,for example, so that the user apparatus UE2 on the receiving side canidentify repeated transmissions from the same user apparatus UE1 andreceive the discovery messages by HARQ soft combining of segment #1.Furthermore, the user apparatus UE1 on the transmitting side maydetermine the time/frequency resource pattern of the discovery messageby itself, transmit the information of the determined time/frequencyresource pattern by a sidelink control channel (that is, by SCI), andtransmit a discovery message by the time/frequency resource pattern.

Hereinafter, the contents of the discovery message will be described inmore detail by taking a discovery message including segment #1 andsegment #2 as illustrated in FIG. 16, as an example.

<Content Example of Discovery Message>

Segment #1 includes AS parameters that are not frequently updated.Examples of the AS parameters are as follows. Segment #1 includes one orany plurality of or all of the following parameters:

Transmission parameters for transmitting a discovery message, and/ortransmission parameters for transmitting control information in D2Dcommunication, and/or transmission parameters for data transmission inD2D communication (transmission parameters are parameters used on thetransmitting side; for example, transmission power, transmissioncarrier, MCS, resource size, reference signal configuration, etc.).

Reception parameters for receiving discovery messages, and/or receptionparameters for receiving control information, and/or receptionparameters for data reception (a reception parameter means a parameterused by the transmitting side of the discovery message when receivinginformation from another UE; for example, a reception beampattern/index, and a reception carrier, etc. Furthermore, the receptionparameter may be a parameter used by the receiving side of the discoverymessage when receiving information).

Segment #2 includes information that may be updated each time adiscovery message is transmitted. The information is, for example, oneor any plurality of or all of the position, the speed, the headingdirection, the acceleration, etc., of the user apparatus UE1transmitting the discovery message. Furthermore, the AS parameters maybe included in segment #2.

By multiplexing segment #1 and segment #2 to obtain a discovery message,the user apparatus UE2 on the receiving side can identify that the twosegments have been transmitted from the same user apparatus UE.

For example, the user apparatus UE2 that performs transmission in D2Dcommunication by receiving the discovery message, can determine thedestination UE based on the position of the UE detected in segment #2and adjust transmission parameters when transmitting controlinformation/data to the destination UE based on the AS parameters ofsegment #1.

In the embodiment 2, there are types 1 and 2 described below astransmission types.

<Type 1>

In type 1, the user apparatus UE1 transmits a discovery message withouttransmitting control information for receiving a discovery message onthe receiving side. For example, the discovery message is transmittedaccording to the time/frequency resource set, MCS, a hopping pattern,etc., which have been (pre) configured or predefined. The user apparatusUE2 on the receiving side performs blind detection of the discoverymessage.

<Type 2>

In Type 2, the user apparatus UE1 transmits a discovery message togetherwith control information for receiving a discovery message on thereceiving side. That is, transmission is performed by the same method asD2D communication. The control information includes, for example, anindication of the time/frequency resource and an indication of MCS.Before the process of receiving the discovery message, the userapparatus UE2 on the receiving side decodes the control information andperforms a reception process (demodulation, decoding) by using thecontrol information.

The control information in type 2 may be referred to as schedulinginformation. The control information in type 2 may be used for thescheduling of only segment #2 or may be used for the scheduling ofsegment #1 and segment #2 or may be used for the scheduling of onlysegment #1.

<Regarding Channels to be Used>

As an example, segment #1 is transmitted on a control channel (that is,PSCCH) and segment #2 is transmitted on the data channel (that is,PSSCH).

For example, in addition to the SCI format for data scheduling, an SCIformat for discovery message scheduling may be defined. Furthermore, forexample, the SCI (segment #1) of SCI format for discovery messagescheduling may not include parameters relating to link adaptation ofdata (for example, MCS, RI, PMI). Furthermore, it may be assumed thatthe data resource size (for example, the resource size of segment #2) isfixed.

As described above, information (indication) indicating that the SCI issegment #1 may be included in the SCI by using the free area in the SCIthat does not include parameters relating to the link adaptation.Alternatively, the user apparatus UE2 on the receiving side maydetermine that the SCI that does not include the parameter relating tothe link adaptation, indicates segment #1.

The flag in the SCI, the payload size of the SCI, or the CRC mask may beused to identify the type of SCI (for discovery messages or for D2Dcommunication).

<Example of Procedure for Transmitting Discovery Message>

Next, an example of a procedure of transmitting a discovery messageexecuted by the user apparatus UE1 on the transmitting side will bedescribed with reference to FIGS. 17 to 19. The transmission processesillustrated in FIGS. 17 to 19 are processes executed by a transmissionunit 101 in the user apparatus UE1 to be described later.

FIG. 17 illustrates an example of Type 1. As illustrated in FIG. 17,channel coding is performed on the information of segment #1 (the bitstring to which the CRC is added) (step S1). At the same time, channelcoding is performed on the information of segment #2 (the bit string towhich the CRC is added) (step S2), and rate matching and code blockconcatenation are performed on the channel coded information (steps S3,S4). Note that steps S3 and S4 may not be executed. The information ofsegment #1 processed in step S1 and the information of segment #2processed in steps S1 to S4 are multiplexed (step S5), channelinterleaved (step S6), and a discovery message is generated.Subsequently, by performing scrambling, modulation, and mapping toresources, etc., the discovery message is transmitted from the antennaas a radio signal. Note that channel interleaving may not be performed.

In the example illustrated in FIG. 17, on the receiving side, segment #1is detected regardless of whether segment #2 is detected.

FIG. 18 illustrates an example of Type 2. As illustrated in FIG. 18, theprocess for the sidelink control channel and the process for thesidelink data channel are performed.

In the process for the sidelink control channel, the information of theSCI for data scheduling (the bit string to which the CRC is added) andthe information of segment #1 (the bit string to which the CRC is added)are channel-coded (steps S11, S12), and multiplexed (step S13).

In the process for the sidelink data channel, channel coding, ratematching, code block concatenation, and channel interleaving areexecuted on the information of segment #2 (bit string to which CRC isadded) (steps S14 to S17).

The SCI and segment #1 that have been multiplexed in step S13, andsegment #2 that has undergone the processes of steps S14 to S17, aremultiplexed (step S18). Subsequently, the SCI and the discovery messageare transmitted as radio signals from the antenna by performingscrambling, modulation, mapping to resources, etc.

In the example illustrated in FIG. 18, on the receiving side, segment #1can be detected regardless of whether SCI for data scheduling isdetected.

FIG. 19 illustrates another example of type 2. As illustrated in FIG.19, the process for the sidelink control channel and the process for thesidelink data channel are performed. However, unlike the example of FIG.18, in the example of FIG. 19, both segment #1 and segment #2 aretransmitted on the data channel.

In the process for the sidelink control channel, SCI information fordata scheduling (bit string to which CRC is added) is channel-coded(step S21).

In the process for the sidelink data channel, the information of segment#1 (the bit string to which the CRC is added) is channel-coded (stepS22). Furthermore, channel coding, rate matching, and code blockconcatenation are executed on the information of segment #2 (bit stringto which CRC is added) (steps S23 to S25). Segment #1 that has undergonethe process of S22 and segment #2 that has undergone the processes ofsteps S23 to S25 are multiplexed and channel interleaved (steps S26,S27). Then, the SCI and multiplexed segment #1 and segment #2, aremultiplexed (step S28). Subsequently, the SCI and the discovery messageare transmitted as radio signals from the antenna by performingscrambling, modulation, mapping to resources, etc.

In the example illustrated in FIG. 19, on the receiving side, segment #1is detected when the SCI is correctly detected. Furthermore, in theexample illustrated in FIG. 19, better time/frequency diversity isobtained for segment #1 than in other examples.

<Transmission Example of Discovery Message>

Next, a transmission example of a discovery message will be describedwith reference to FIGS. 20 to 24. In FIGS. 20 to 24, the horizontal axisrepresents time and the vertical axis represents frequency, asillustrated. Furthermore, the illustrated “No modification period”indicates a period during which there are no changes in the reportcontent of segment #1. For example, the user apparatus UE2 on thereceiving side can identify that HARQ soft combining of segment #1 ispossible within “No modification period”. Furthermore, the userapparatus UE2 on the receiving side may regard the parameters in segment#1 that have once been successfully detected in “No modificationperiod”, as valid within the “No modification period”. Note that thenumber of times of transmitting the discovery message in “Nomodification period” in FIGS. 20 to 24, is merely one example. Thenumber of transmissions may be larger than the number of transmissionsillustrated in FIGS. 20 to 24.

FIG. 20 illustrates a transmission example of type 1. As illustrated inFIG. 20, in the first “No modification period”, a discovery messageindicated by A and a discovery message indicated by B are transmitted.As described in C and D, the resources in multiple transmissions aredetermined, for example, based on a predetermined hopping pattern.

The illustrated A1 and B1 are segment #1, and A2 and B2 are segment #2,respectively. Within “No modification period”, A1 and B1 are the samepayload (information in which the same contents are encoded).Furthermore, A1 and B1 have a fixed size and a fixed MCS. However, RVcan change between A1 and B1. A2 and B2 are payloads that may be changedeach time the transmission is performed. The size and the MCS may befixed or may be changed each time the transmission is performed.

The user apparatus UE2 on the receiving side can receive segment #1 byperforming soft combining of HARQ (for example, incremental redundancy(IR) combining) by using A1 and B1.

Also in the next “No modification period”, as indicated by C and D, thediscovery message is transmitted similar to the case of the first “Nomodification period”.

FIG. 21 illustrates a transmission example of type 2. As illustrated inFIG. 21, in “No modification period”, SCI+discovery message indicated byA, SCI+discovery message indicated by B, and SCI+discovery messageindicated by C are transmitted. Resources for multiple transmissions aredetermined, for example, based on a predetermined hopping pattern.

The illustrated A1, B1, and C1 are SCIs for data scheduling (schedulingof segment #1 and/or segment #2), respectively.

The illustrated A2, B2, and C2 are segment #1, and A3, B3, and C3 aresegment #2, respectively. Within “No modification period”, A2, B2 and C3are the same payload (information in which the same contents areencoded). A3, B3, and C3 are payloads that may be changed each time thetransmission is performed. The size and MCS in A3, B3, C3 may be changedeach time the transmission is performed.

The user apparatus UE2 on the receiving side can perform soft combiningof HARQ by using A2, B2, and C2 to receive segment #1.

FIG. 22 also illustrates a transmission example of type 2. Asillustrated in FIG. 22, SCI+discovery message indicated by A andSCI+discovery message indicated by B are transmitted in “No modificationperiod”. Resources for multiple transmissions are determined, forexample, based on a predetermined hopping pattern.

The illustrated A1 and B1 are SCIs for data scheduling (scheduling ofsegment #2), respectively. The payload of this SCI can be changed eachtime the transmission is performed.

The illustrated A2 and B2 are segment #1, and A3 and B3 are segment #2,respectively. Within “No modification period”, A2 and B2 are the samepayload (information in which the same contents are encoded). A3, B3 arepayloads that can be changed each time the transmission is performed.The size and MCS in A3, B3 can be changed each time the transmission isperformed.

In the example of FIG. 22, SCI and segment #1 are transmitted on thesidelink control channel and segment #2 is transmitted on the sidelinkdata channel, as illustrated.

FIG. 23 also illustrates a transmission example of type 2. In theexample of FIG. 23, the SCI includes ID=A that is the ID of thetransmission source that executes the discovery. Otherwise, this exampleis the same as the example of FIG. 22.

Upon detecting ID=A in the received SCI, the user apparatus UE2 on thereceiving side can identify that the data scheduled by this SCI issegment #2 of the discovery message transmitted from the UE with ID=A.

FIG. 24 also illustrates a transmission example of type 2. Asillustrated in FIG. 24, in “No modification period”, SCI+discoverymessage indicated by A, SCI+discovery message indicated by B, andSCI+discovery message indicated by C are transmitted. Resources formultiple transmissions are determined, for example, based on apredetermined hopping pattern.

The illustrated A1, B1, C1 are SCIs for data scheduling (scheduling ofsegment #1 and/or segment #2), respectively.

The illustrated A2, B2, and C2 are segment #1, and A3, B3, and C3 aresegment #2, respectively. Within “No modification period”, A2, B2, andC3 are the same payload (information in which the same contents areencoded). A3, B3, and C3 are payloads that can be changed each time thetransmission is performed. The size and MCS in A3, B3, and C3 can bechanged each time the transmission is performed.

In the example of FIG. 24, soft combining is possible for segment #1with A2, B2, and C2. Furthermore, in the example of FIG. 24, forexample, by the second transmission of SCI, it is indicated that segment#2 is transmitted again, and therefore it is possible to perform softcombining of segment #2 (A3) of the first transmission and segment #2(B3) of the second transmission.

<Regarding Multiplexing Method, Encoding, Etc.>

In FIGS. 20 to 24, examples in which segment #1 and segment #2 arefrequency-multiplexed (FDM) are illustrated; however, these are onlyexamples. Segment #1 and segment #2 may be time division multiplexed(TDM) or code division multiplexed (CDM).

Furthermore, in FIG. 20 to FIG. 24, examples in which the SCI andsegment #1 are frequency multiplexed (FDM) are illustrated; however,this is only an example. The SCI and segment #1 may be time divisionmultiplexed (TDM) or code division multiplexed (CDM). Furthermore,segment #1 may be used for the scheduling of segment #2.

Regarding encoding, for example, MCS, the encoding rate (or MCS offset,encoding rate offset), etc., are set (or preset) in the user apparatusUE from base station 10, with respect to each of segment #1 and segment#2. Furthermore, a value defined by a specification, etc., may be set inthe user apparatus UE.

As an example, when different reliabilities are required for segment #1and segment #2 (for example, segment #2 has a higher reliability), it isconsidered that the encoding rate of either segment #1 or segment #2 isset to be lower than the other (for example, the encoding rate ofsegment #2 is lowered when segment #2 has higher reliability).

<Regarding Modification Period>

Regarding the modification period (corresponding to the No modificationperiod in FIGS. 20 to 24), it is necessary for the user apparatuses UEsto share a common recognition regarding the start timing (time offset)and the time length. Therefore, the modification period is determinedbased on a predetermined reference time, etc. The reference time is, forexample, UTC-time, a frame number, a subframe number, and a slot number,etc. Furthermore, the period (time length) and the time offset of themodification period may be (pre) configured in the user apparatus UE.

<Regarding Validation of Segment #1>

There are the following options 1 to 4 for confirming the validity ofsegment #1 in the user apparatus UE2 on the receiving side.

Option 1) The user apparatus UE2 determines that the most recently(latest) detected segment #1 is valid. That is, every time segment #1 isdetected, it is determined that segment #1 is valid.

Option 2) The user apparatus UE2 determines that segment #1 detected inthe nth modification period is valid in the (n+m)th modification period.For example, m=1. Furthermore, m may be configured from the base station10 or may be preconfigured. Also, m may be indicated by a discoverymessage (segment #1 and/or segment #2).

Option 3) When the user apparatus UE2 detects that a change has beenmade in the DMRS sequence in the received discovery message or in apredetermined portion in the received discovery message, the userapparatus UE2 determines that segment #1 has been changed.

Option 4) When the user apparatus UE2 detects that the modificationindicator in the SCI for discovery message scheduling indicates “noupdate”, the user apparatus UE2 determines that segment #1 detectedimmediately before is valid. For example, in the example of FIG. 21, ifthe modification indicator in SCI in B indicates “no update”, the userapparatus UE2 determines that segment #1 in A is valid.

<Regarding Validation of Segment #2>

The user apparatus UE2 on the receiving side, for example, determinesthat segment #2 detected most recently (latest) is valid. That is, everytime segment #2 is detected, it is determined that the detected segment#2 is valid.

The embodiment 2 uses a discovery message, in which segment #1 that canbe soft combined and that includes information that is not frequentlychanged, and segment #2 including information that may change every timemessage transmission is performed, are multiplexed, and therefore evenwhen the information to be transmitted may be changed frequently, theuser apparatus UE on the transmitting side can appropriately transmitmessages. Furthermore, the user apparatus UE on the receiving sideaccurately identifies parameters (for example, parameters for receptionof segment #2 and parameters for D2D communication transmission) insegment #1, and therefore the user apparatus UE on the receiving sidecan appropriately receive segment #2 and appropriately determine thedestination UE in the D2D communication and execute transmission in D2Dcommunication to the destination UE, etc. Note that also in theembodiment 2, the user apparatus UE2 on the receiving side can performthe measurement in the same manner as the measurement using thediscovery message in the embodiment 1.

(Association Between Discovery and D2D Communication)

Next, the association between discovery and D2D communication will bedescribed. The contents here can be applied to both of the embodiment 1and the embodiment 2.

When the user apparatus UE2 on the receiving side detects the locationof the transmission source UE, the user apparatus UE2 on the receivingside can selectively receive the data of the D2D communicationtransmitted from a plurality of transmission source UEs. As methods forperforming this, there are the following options 1 and option 2 (option2-1, 2-2).

Option 1) Information on time/frequency resources of D2D communicationis included in the discovery message transmitted from the user apparatusUE on the transmitting side. The time/frequency resources are, forexample, resources used by the user apparatus UE1 for transmission(transmission of control information and/or data) in D2D communication.Note that the time/frequency resources used for transmitting thediscovery message and the time/frequency resources used for transmissionin the D2D communication may be different.

For example, as illustrated in FIG. 25, the user apparatus UE2 on thereceiving side can receive the control information/data of the D2Dcommunication by using the time/frequency resources for D2Dcommunication included in the received discovery message.

Option 2) In option 2, the ID (discovery ID) of the user apparatus UE onthe transmitting side included in the discovery message transmitted fromthe user apparatus UE on the transmitting side, is used for reception ofcontrol information/data in D2D communication at the UE on the receivingside. Specifically, there are the following options 2-1 and 2-2.

In option 2-1, the CRC of the SCI used for the data scheduling in D2Dcommunication is masked by a UE-ID (or a processed UE-ID). The userapparatus UE2 on the receiving side can receive the SCI and the data byunmasking the CRC with the UE-ID acquired by the discovery message.

In option 2-2, SCI used for data scheduling in D2D communication or datais scrambled by the UE-ID (or a processed UE-ID). The user apparatus UE2on the receiving side can receive the SCI and the data by descramblingthe SCI/data with the UE-ID acquired by the discovery message. Note thatthe above “processed” means, for example, setting the bit length of theUE-ID to a predetermined bit length.

(Regarding Cross Carrier Discovery)

The content here can also be applied to both the embodiment 1 and theembodiment 2. In the discovery message, the AS parameters for D2Dcommunication and frequencies used for transmission and/or reception inD2D communication may be included.

Furthermore, the transmission of the discovery message and thetransmission in D2D communication associated with the discovery may beperformed at different frequencies with different RATs. For example, D2Dcommunication may be performed with NR sidelink and the discovery may beperformed with LTE V2X or IEEE 802.11p.

For example, when the discovery message is transmitted at a frequencythat is lower than the frequency used in the D2D communication, asufficient discovery range can be obtained without HARQ combining.

(Device Configuration)

Next, a functional configuration example of the user apparatus UE andthe base station 10 that execute the processing operations described sofar will be described. The user apparatus UE and the base station 10 mayinclude all the functions of the embodiment 1 and the embodiment 2, ormay include the functions of only one of the embodiments.

<User Apparatus>

FIG. 26 is a diagram illustrating an example of the functionalconfiguration of the user apparatus UE. As illustrated in FIG. 26, theuser apparatus UE includes a transmitting unit 101, a receiving unit102, and a configuration information managing unit 103. The functionalconfiguration illustrated in FIG. 26 is merely an example. As long asthe operations according to the present embodiment can be executed, thefunctional sections and the names of the functional units are notlimited to this example.

The transmitting unit 101 creates a transmission signal from thetransmission data and wirelessly transmits the transmission signal. Thereceiving unit 102 wirelessly receives various signals, and acquires asignal of a higher layer from the signal of the received physical layer.Both the transmitting unit 101 and the receiving unit 102 include a D2Dfunction and a cellular communication function. The transmitting unit101 includes a function of executing the operations ofmessage/SCI/data/signal transmission described in the embodiments 1 and2, and the receiving unit 102 includes a function of executing theoperations of message/SCI/data/signal reception described in theembodiments 1 and 2.

The configuration information managing unit 103 stores various kinds ofconfiguration information received from the base station 10 by thereceiving unit 102 and preset configuration information.

Furthermore, as illustrated in FIG. 27, the transmitting unit 101includes a message generating unit 111, a message transmitting unit 121,and a signal transmitting unit 131. For example, as illustrated in FIGS.17 to 19, the message generating unit 111 generates a discovery message.The message transmitting unit 121 transmits the discovery message in theembodiments 1 and 2, and the signal transmitting unit 131 transmits thediscovery signal in the embodiment 1.

Furthermore, the signal transmitting unit 131 is configured to transmita signal used for measurement of the radio quality in another userapparatus, and the message transmitting unit 121 is configured totransmit a message including a predetermined parameter, and thetransmission period of signals transmitted by the signal transmittingunit 131 may be independent of the transmission period of messagestransmitted by the message transmitting unit 121. Furthermore, thereceiving unit 102 may be configured to receive, from the base station10, parameters used for receiving signals transmitted from other userapparatuses.

Furthermore, the message generating unit 111 is configured to generate amessage including a first segment and a second segment, and the messagetransmitting unit 121 is configured to transmit the message a pluralityof times within a predetermined period, and the information reported bya plurality of first segments transmitted within the predeterminedperiod by the message transmitting unit 121, may not be changed withinthe predetermined period.

The message transmitting unit 121 may be configured to transmit controlinformation including scheduling information of the second segment, orcontrol information including scheduling information of the firstsegment and the second segment, and the message.

The message transmitting unit 121 may be configured to transmit thefirst segment by using a control channel and transmit the second segmentby using a data channel.

The message transmitting unit 121 may be configured to transmit themessage a plurality of times within the predetermined period, by using apredetermined resource hopping pattern or a resource hopping pattern setfrom the base station in the radio communication system.

<Base Station 10>

FIG. 28 is a diagram illustrating an example of the functionalconfiguration of the base station 10. As illustrated in FIG. 28, thebase station 10 includes a transmitting unit 201, a receiving unit 202,and a configuration information managing unit 203. The functionalconfiguration illustrated in FIG. 28 is merely an example. As long asthe operations according to the present embodiment can be executed, thefunctional sections and the names of the functional units are notlimited to this example.

The transmitting unit 201 includes a function of generating a signal tobe transmitted to the user apparatus UE side and wirelessly transmittingthe signal. The receiving unit 202 includes a function of receivingvarious signals transmitted from the user apparatus UE and acquiring,for example, information of a higher layer, from the received signals.

The transmitting unit 201 includes a function of executing operationsfor transmitting signals such as configuration information, etc., to theuser apparatus UE described in the embodiments 1 and 2, and thereceiving unit 202 includes a function of executing operations forreceiving signals from the user apparatus UE. The operations of signaltransmission include scheduling.

The configuration information managing unit 203 stores various kinds ofconfiguration information to be transmitted to the user apparatus UE,various kinds of configuration information received from the userapparatus UE, and configuration information preset.

<Hardware Configuration>

The block diagrams (FIGS. 26 to 28) used in the description of the aboveembodiment illustrate blocks of functional units. These functionalblocks (constituent parts) are implemented by any combination ofhardware and/or software. Furthermore, the means for implementing eachfunctional block is not particularly limited. That is, the respectivefunctional blocks may be implemented by a single device in which aplurality of elements are physically and/or logically combined; or twoor more devices, which are physically and/or logically separated, may bedirectly and/or indirectly (for example, wired and/or wireless)connected, and the respective functional blocks may be implemented bythese plural devices.

Furthermore, for example, both the user apparatus UE and the basestation 10 according to one embodiment of the present invention mayfunction as a computer that performs processes according to the presentembodiment. FIG. 29 is a diagram illustrating an example of a hardwareconfiguration of the user apparatus UE and the base station 10 accordingto the present embodiment. Each of the user apparatus UE and the basestation 10 described above may be physically configured as a computerdevice including a processor 1001, a memory 1002, a storage 1003, acommunication device 1004, an input device 1005, an output device 1006,and a bus 1007, etc.

Note that in the following description, the term “device” can be read asa circuit, a device, and a unit, etc. The hardware configuration of theuser apparatus UE and the base station 10 may be configured to includeone or a plurality of devices indicated by the reference numerals 1001to 1006 illustrated in the drawing, or may be configured to not includesome of the devices.

The respective functions of the user apparatus UE and the base station10 are implemented by having predetermined software (programs) to beloaded in the hardware such as the processor 1001 and the memory 1002 sothat the processor 1001 performs computation and controls thecommunication performed by the communication device 1004 and the readingand/or writing of data in the memory 1002 and the storage 1003.

The processor 1001, for example, operates the operating system tocontrol the entire computer. The processor 1001 may be configured with aCentral Processing Unit (CPU) including an interface with peripheraldevices, a control device, an arithmetic device, and a register, etc.

Furthermore, the processor 1001 loads programs (program codes), softwaremodules, or data from the storage 1003 and/or the communication device1004 into the memory 1002, and executes various processes according tothese elements. As the program, a program for causing a computer toexecute at least part of the operation described in the aboveembodiment, is used. For example, the transmitting unit 101, thereceiving unit 102, and the configuration information managing unit 103of the user apparatus UE illustrated in FIG. 26 may be implemented by acontrol program that is stored in the memory 1002 and that operates onthe processor 1001. Furthermore, for example, the transmitting unit 201,the receiving unit 202, and the configuration information managing unit203 of the base station 10 illustrated in FIG. 28 may be implemented bya control program that is stored in the memory 1002 and that operates onthe processor 1001. Although it has been described that the variousprocesses described above are executed by a single processor 1001, thevarious processes described above may be executed simultaneously orsequentially by two or more processors 1001. The processor 1001 may beimplemented by one or more chips. Note that the programs may betransmitted from the network via an electric communication line.

The memory 1002 is a computer-readable recording medium, and isconfigured with at least one of a ROM (Read-Only Memory), an EPROM(Erasable Programmable ROM), an EEPROM (Electrically ErasableProgrammable ROM), and a RAM (Random Access Memory), for example. Thememory 1002 may be referred to as a register, a cache, and a main memory(main memory), etc. The memory 1002 can store executable programs(program codes) and software modules, etc., for implementing theprocesses according to an embodiment of the present invention.

The storage 1003 is a computer-readable recording medium, and may beconfigured with at least one of, for example, an optical disk such as aCD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, amagneto-optical disk (for example, a compact disk, a digital versatiledisk, a Blu-ray (Registered trademark) disk), a smart card, a flashmemory (for example, a card, a stick, a key drive), a floppy (registeredtrademark) disk, and a magnetic strip, etc. The storage 1003 may bereferred to as an auxiliary storage device. The above-described storagemedium may be, for example, a database including the memory 1002 and/orthe storage 1003, a server, or other appropriate media.

The communication device 1004 is hardware (transmission/receptiondevice) for performing communication between computers via a wiredand/or wireless network, and is also referred to as a network device, anetwork controller, a network card, and a communication module, etc.,for example. For example, the transmitting unit 101 and the receivingunit 102 of the user apparatus UE may be implemented by thecommunication device 1004. Furthermore, the transmitting unit 201 andthe receiving unit 202 of the base station 10 may be implemented by thecommunication device 1004.

The input device 1005 is an input device (for example, a keyboard, amouse, a microphone, a switch, a button, and a sensor, etc.) thataccepts input of information from the outside. The output device 1006 isan output device (for example, a display, a speaker, and an LED lamp,etc.) that outputs information to the outside. Note that the inputdevice 1005 and the output device 1006 may be integrated (for example, atouch panel).

Furthermore, the respective devices such as the processor 1001 and thememory 1002 are connected by the bus 1007 for communicating information.The bus 1007 may be configured with a single bus or may be configuredwith different buses between the respective devices.

Furthermore, each of the user apparatus UE and the base station 10 mayinclude hardware such as a microprocessor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a programmablelogic device (PLD), and a field programmable gate array (FPGA), and someof or all of the functional blocks may be implemented by this hardware.For example, the processor 1001 may be implemented with at least one ofthese hardware elements.

(Summary of Embodiment)

As described above, according to the present embodiment, a userapparatus in a radio communication system supporting a D2D technology isprovided, the user apparatus including

a signal transmitting unit configured to transmit a signal used formeasuring a radio quality in another user apparatus; and

a message transmitting unit configured to transmit a message including apredetermined parameter, wherein

a transmission period of the signals transmitted by the signaltransmitting unit is independent of a transmission period of themessages transmitted by the message transmitting unit.

According to the above configuration, a technology for enabling a userapparatus to appropriately measure the radio quality, while avoiding anincrease in the overhead of radio resources in D2D, is provided.

The predetermined parameter may include a parameter used for receivingthe signal. According to this configuration, the user apparatus on thereceiving side can appropriately receive the signals.

A transmission parameter of the signal may be derived from atransmission parameter of the message, or the transmission parameter ofthe message may be derived from the transmission parameter of thesignal. According to this configuration, the signaling overhead can bereduced.

The signal may be a physical signal that does not include a message.According to this configuration, the signal can be transmitted with asmall number of radio resources.

The user apparatus may further include a receiving unit configured toreceive, from a base station in the radio communication system, aparameter used for receiving a signal transmitted from the other userapparatus. According to this configuration, signals transmitted from theother user apparatus can be appropriately received.

Furthermore, according to the present embodiment, a transmission methodexecuted by a user apparatus in a radio communication system supportinga D2D technology is provided, the transmission method including

a signal transmitting step of transmitting a signal used for measuring aradio quality in another user apparatus; and

a message transmitting step of transmitting a message including apredetermined parameter, wherein

a transmission period of the signals transmitted at the signaltransmitting step is independent of a transmission period of themessages transmitted at the message transmitting step.

According to the above configuration, a technology for enabling a userapparatus to appropriately measure the radio quality, while avoiding anincrease in the overhead of radio resources in D2D, is provided.

Furthermore, as described above, according to the present embodiment, auser apparatus in a radio communication system supporting a D2Dtechnology is provided, the user apparatus including

a message generating unit configured to generate a message including afirst segment and a second segment; and

a message transmitting unit configured to transmit, multiple times, themessage within a predetermined period, wherein

information reported by a plurality of the first segments transmittedwithin the predetermined period by the message transmitting unit, is notchanged within the predetermined period.

According to the above configuration, a technology for enabling messagesto be appropriately transmitted and received, even when the information,which is transmitted in the message by the user apparatus on thetransmitting side, may be frequently changed, in D2D, is provided.

The message transmitting unit may transmit control information includingscheduling information of the second segment or control informationincluding scheduling information of the first segment and the secondsegment, and the message. According to this configuration, the userapparatus on the receiving side can quickly receive the message.

The message transmitting unit may transmit the first segment by using acontrol channel, and transmit the second segment using a data channel.According to this configuration, for example, it is possible to use anexisting channel and implementation is relatively easy.

The message transmitting unit may transmit, multiple times, the messagewithin the predetermined period, by using a predetermined resourcehopping pattern or a resource hopping pattern set from a base station inthe radio communication system. According to this configuration, theuser apparatus on the receiving side can appropriately receive themessage.

HARQ soft combining may be executed at another user apparatus, withrespect to a plurality of the first segments transmitted within thepredetermined period by the message transmitting unit. According to thisconfiguration, the other user apparatus can properly receive the firstsegment.

Furthermore, according to the present embodiment, a transmission methodexecuted by a user apparatus in a radio communication system supportinga D2D technology is provided, the transmission method including

a message generating step of generating a message including a firstsegment and a second segment; and

a message transmitting step of transmitting, multiple times, the messagewithin a predetermined period, wherein

information reported by a plurality of the first segments transmittedwithin the predetermined period at the message transmitting step, is notchanged within the predetermined period.

According to the above configuration, a technology for enabling messagesto be appropriately transmitted and received, even when the information,which is transmitted in the message by the user apparatus on thetransmitting side, may be frequently changed, in D2D, is provided.

(Supplement to Embodiment)

The exemplary embodiment of the present invention is described above,but the disclosed invention is not limited to the above embodiment, andthose skilled in the art would understand that various modifiedexamples, revised examples, alternative examples, substitution examples,and the like can be made. In order to facilitate understanding of thepresent invention, specific numerical value examples are used fordescription, but the numerical values are merely examples, and certainsuitable values may be used unless otherwise stated. The classificationof items in the above description is not essential to the presentinvention, matters described in two or more items may be combined andused as necessary, and a matter described in one item may be applied toa matter described in another item (unless there is no contradiction).The boundary between functional units or processing units in afunctional block diagram does not necessarily correspond to the boundarybetween physical parts. Operations of a plurality of functional unitsmay be performed physically by one component, or an operation of onefunctional unit may be performed physically by a plurality of parts. Inthe processing procedures described in the embodiment, the order ofprocesses may be changed as long as there is no inconsistency. For thesake of convenience of description, the user apparatus UE and the basestation 10 have been described using the functional block diagrams, butsuch apparatuses may be implemented by hardware, software, or acombination thereof. Software executed by the processor included in theuser apparatus UE according to the embodiment of the present invention,and the software executed by the processor of the base station 10according to the embodiment of the present invention, may be stored in arandom access memory (RAM), a flash memory, a read only memory (ROM), anEPROM, an EEPROM, a register, a hard disk (HDD), a removable disk, aCD-ROM, a database, a server, or any other appropriate storage medium.

Furthermore, notification of information is not limited to theaspect/embodiment described in the present specification, and may beperformed by other methods. For example, the notification of informationmay be performed by physical layer signaling (for example, DCI (DownlinkControl Information), UCI (Uplink Control Information)), upper layersignaling (for example, RRC (Radio Resource Control) signaling, MAC(Medium Access Control) signaling, broadcast information (MIB (MasterInformation Block), SIB (System Information Block)), other signals, or acombination of these methods. Furthermore, the RRC signaling may bereferred to as an RRC message, and may be, for example, an RRCConnection Setup message or an RRC Connection Reconfiguration message,etc.

Each aspect/embodiment described in the present specification may beapplied to LTE (Long Term Evolution), LTE-A (LIE-Advanced), SUPER 3G,IMT-Advanced, 4G, 5G, FRA (Future Radio Access), W-CDMA (registeredtrademark), GSM, (registered trademark), CDMA2000, UMB (Ultra MobileBroadband), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, UWB(Ultra-WideBand), Bluetooth(registered trademark), and a system usingother appropriate systems and/or a next generation system expanded basedon these systems.

In the processes, sequences, and flowcharts, etc., in eachaspect/embodiment described in the present specification, the order ofprocesses may be exchanged, as long as there is no inconsistency. Forexample, for the methods described in the present specification,elements of the various steps are presented in an exemplary order andare not limited to the presented specific order.

The specific operation that is performed by the base station 10 in thepresent specification may be performed by an upper node of the basestation 10 in some cases. It is obvious that in a network including oneor more network nodes including the base station 10, various operationsperformed for communication with the user apparatus UE, may be performedby the base station 10 and/or a network node of other than the basestation 10 (for example, MME or S-GW, etc., although not limited assuch). In the above example, there is one network node other than thebase station 10; however, a combination of a plurality of other networknodes (for example, MME and S-GW) may be used.

Each aspect/embodiment described in the present specification may beused singly or in combination, or may be switched in accordance withexecution.

The user apparatus UE may be referred to, by those skilled in the art,as a subscriber station, a mobile unit, a subscriber unit, a wirelessunit, a remote unit, a mobile device, a wireless device, a wirelesscommunication device, a remote device, a mobile subscriber station, anaccess terminal, a mobile terminal, a wireless terminal, a remoteterminal, a handset, a user agent, a mobile client, a client, or someother suitable term.

The base station 10 may be referred to, by those skilled in the art, asa NB (Node B), an eNB (enhanced Node B), a Base Station, gNB, or someother suitable term.

The terms “determining” and “deciding” used in the present specificationmay encompass a wide variety of operations. “Determining” and “deciding”may include the meaning of, for example, judging, calculating,calculating, computing, processing, deriving, investigating, looking up(for example, searching a table, a database, or another data structure),and ascertaining, etc. Furthermore, “determining” and “deciding” mayinclude the meaning of receiving (for example, receiving information),transmitting (for example, transmitting information), inputting,outputting, and accessing (for example, accessing data in a memory).Furthermore, “determining” and “deciding” may include the meaning ofresolving, selecting, choosing, establishing, and comparing, etc. Inother words, “determining” and “deciding” include the meaning of“determining” and “deciding” some kind of operation.

The phrase “based on” used in the present specification does not mean“based only on”, unless explicitly stated otherwise. In other words, thephrase “based on” means both “based only on” and “based on at least”.

The terms “include”, “including”, and variations thereof used in thepresent specification or claims, are intended to be inclusive in amanner similar to the term “comprising”. Furthermore, the term “or” usedin the present specification or claims, is not intended to be exclusiveOR.

In the entire present disclosure, if articles are added by translation,such as a, an, and the in English, for example, these articles mayinclude a plural number of items/units, unless it is indicated thatthese articles are obviously not plural from the context.

Although the present invention has been described in detail above, itwill be obvious to those skilled in the art that the present inventionis not limited to the embodiments described herein. The presentinvention can be implemented as modifications and variations withoutdeparting from the spirit and scope of the present invention as definedby the scope of the claims. Therefore, the description of the presentspecification is for the purpose of illustration and does not have anyrestrictive meaning to the present invention.

REFERENCE SIGNS LIST

-   UE user apparatus-   101 transmitting unit-   111 message generating unit-   121 message transmitting unit-   131 signal transmitting unit-   102 receiving unit-   103 configuration information managing unit-   10 base station-   201 transmitting unit-   202 receiving unit-   203 configuration information managing unit-   1001 processor-   1002 memory-   1003 storage-   1004 communication device-   1005 input device-   1006 output device

1. A user apparatus in a radio communication system supporting a D2Dtechnology, the user apparatus comprising: a message generating unitconfigured to generate a message including a first segment and a secondsegment; and a message transmitting unit configured to transmit,multiple times, the message within a predetermined period, whereininformation reported by a plurality of the first segments transmittedwithin the predetermined period by the message transmitting unit, is notchanged within the predetermined period.
 2. The user apparatus accordingto claim 1, wherein the message transmitting unit transmits controlinformation including scheduling information of the second segment, orcontrol information including scheduling information of the firstsegment and the second segment, and the message.
 3. The user apparatusaccording to claim 1, wherein the message transmitting unit transmitsthe first segment by using a control channel, and transmits the secondsegment using a data channel.
 4. The user apparatus according to claim1, wherein the message transmitting unit transmits, multiple times, themessage within the predetermined period, by using a predeterminedresource hopping pattern or a resource hopping pattern set from a basestation in the radio communication system.
 5. The user apparatusaccording to claim 1, wherein HARQ soft combining is executed at anotheruser apparatus, with respect to a plurality of the first segmentstransmitted within the predetermined period by the message transmittingunit.
 6. A transmission method executed by a user apparatus in a radiocommunication system supporting a D2D technology, the transmissionmethod comprising: a message generating step of generating a messageincluding a first segment and a second segment; and a messagetransmitting step of transmitting, multiple times, the message within apredetermined period, wherein information reported by a plurality of thefirst segments transmitted within the predetermined period at themessage transmitting step, is not changed within the predeterminedperiod.